1. Field of the Invention
The present invention is directed to a rotary drill bit for drilling a bore hole in the surface of the earth and more particularly to a drill bit body having an elongated nozzle therein wherein the nozzle is positioned to inject drilling fluid into the bore hole to optimize the cleaning effect of the detritus between the teeth of the cutting head of the drill bit and in the bottom of the bore hole without causing damage to the drill bit seals. The body of the drill bit is formed to provide passages for the upward flow of drilling fluid with detritus therein.
2. Description of the Prior Art
It is well known in the art of drilling to inject drilling fluit into a bore hole in order to remove detritus from between the teeth of a cutting head and from the bottom of the bore hole and to carry the detritus upwards towards the surface.
U.S. Pat. No. 4,154,312, the disclosure of which is incorporated herein by reference, is directed to a rotary drill bit with a solid conical cutting head in which drilling mud or drilling fluid is injected into the bore hole through a circular nozzle located on the side of the drill bit. The flow of drilling mud through the nozzle is such that it removes detritus from between the teeth and from the bottom of the bore hole. In this prior art device, however, the nozzle size is limited by the diameter of the periphery of the drill bit and the requirement to maintain sufficient thickness of the drill bit body and nozzle so that it can withstand the extreme conditions in the bore hole environment. In order to maintain the required thickness of the drill bit body, it is necessary to position the drill bit relatively high on the drill bit body. This results in a spreading of the drilling fluid as it is injected into the bore hole which in turn results in drilling fluid being directed into the drill bit seals. The drilling fluid can have a very damaging effect to the drill bit seals. Furthermore, the drill bit disclosed in U.S. Pat. No. 4,154,312 does not include a body structure which provides passages for the upward flow of detritus and drilling fluid.
U.S. Pat. No. 2,335,929 is directed to a roller bit which includes an elongated nozzle for injecting drilling mud into a bore hole. In this patent, however, the nozzle is positioned with respect to the cutting head such that the drilling mud which flows through the nozzle does not remove the detritus from between the teeth of the cutting head. In this reference, it is necessary to provide an additional passage and nozzle in the body of the drill bit to inject drilling fluid for the purpose of removing the detritus from between the teeth of the drilling head.